DESCRIPTION: Cytochrome P450s are enzymes that metabolize drugs and other potentially toxic compounds in the human body. Without them, toxic chemicals may accumulate to unsafe levels and administered drugs may continue to act indefinitely. Interindividual variation in P450 constituency is one reason for an FDA mandate to pharmaceutical companies, that drug candidates be tested for their potential to induce P450 enzymes. Further, combinatorial chemical technology produces thousands of biologically active compounds daily that require screening for P450 inducibility. To address these needs, this proposal develops a high- volume in vitro assay demonstrating therapeutic-mediated induction of human P450 enzymes. This test system will employ two human P450s, CYP3A4 and 1A2. Both enzymes play major roles in the biostransformation of therapeutic agents and are inducible by a variety of xenobiotics. Regulatory regions of these P450 genes will be ligated to a reporter gene, green fluorescent protein (GFP), and transfected into human tumor cell lines. An "ELISA-like" plate format will be developed for the treatment of transfected cells with candidate drugs. Increased expression of GFP is monitored fluorimetrically and correlates to the drugs' ability to induce a particular P450 enzyme. The ability to predict the behavior of drugs in humans prior to clinical trials, thereby addressing FDA requirements, in a fast and easy format are the hallmarks of this technology. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE